Summer annual broadleaf weed that forms light green, circular mats, up to several feet in diameter, and can spread quickly. Smooth, light green, narrow oval, or tongue-shaped leaves are displayed in whorls around the smooth stem, 3-8 leaves per node. Stems are low-growing with forked branching at nodes. Carpetweed flowers in late summer, from July to September with 2-4 tiny white flowers at the joint between leaf and stem. Spreads by seeds that germinate starting in spring and throughout the growing season. Prefers thin or sandy soils. Found in lawns and gardens.